Superhard materials mainly refer to diamond and cubic boron nitride, whose hardness is far higher than that of other materials. Superhard materials and products thereof are an emerging industry strongly supported by the nation. It is pointed out in Chinese “Twelfth Five-Year” Development Plan for National Strategic Emerging Industries that new functional materials should be vigorously developed, and high-purity graphite, artificial crystals, superhard materials and products thereof should be actively developed. According to the difference of types of binding agents, the superhard material products mainly include: superhard material products with metal binding agents, superhard material products with ceramic binding agents, superhard material products with resin binding agents, superhard material products with electroplated metal binding agents and so on.
As one of the main types of superhard material products, the superhard material products with metal binding agents have the advantages such as strong holding force to abrasive, high strength, good abrasion resistance, good performance of maintaining the shape of a working face, and long service life, and are widely applied to cutting, grinding and shaping and grinding-processing of inorganic non-metal hard and brittle materials such as stones, glasses, ceramics and artificial crystals. However, diamond products with metal binding agents have the problems such as poor self-sharpness, easy blockage, and low grinding efficiency, which limit their use and development.
With regard to the problems of the superhard material products with metal binding agents, numerous investigations and attempts have been made by scholars, primarily adding barren materials including graphite, ceramic, and iron oxide as additive. However, if an excessive quantity of these additives is added, the strength of an abrasive layer and the holding force of the binding agents to the abrasive will be severely reduced, significantly decreasing the service life and easily causing scratches; if the quantity added is too little, the function of improving the grinding performance and the grinding efficiency is not significant.
For example, in the prior art, a superhard abrasive grinding wheel with metal binding agent, which can be subjected to on-line electrolysis, is manufactured by a cold pressing sintering method. One or two additives from graphite and ferroferric oxide, which are used in the superhard abrasive grinding wheel as non-metal additive, have a small adhering function and relatively low strength (being quite different from the metal binding agent in strength), and are unfavorable to keeping the strength of the abrasive layer and the holding force to the abrasive.
Self-sharpness of grinding wheel means that when abrasive grains of the grinding wheel are blunted, the grinding force is also increased accordingly, so that the abrasive grains are broken or fall down, and sharp cutting edges appear again. During the process of grinding of the superhard material product grinding wheel, edges and corners of the abrasive grains of the grinding wheel are gradually rounded and blunted under the effects of friction and extrusion, and abrasive debris is often stuck on the surface of the grinding wheel so that the surface of the grinding wheel is blocked, and finally the grinding wheel loses the grinding ability. At this time, skidding will occur between the grinding wheel and a workpiece, and vibration may be induced and noise may appear, so that the grinding efficiency is decreased and the surface roughness becomes worse. Meanwhile, as the grinding force and the grinding heat are increased, the workpiece will be deformed and the grinding accuracy will be affected, and in severe cases the grinding surface will be burnt and tiny cracks will appear thereon. At this time, the grinding wheel has to be trimmed with a trimmer. The grinding wheel usually needs to be trimmed for tens of minutes or even several hours, severely affecting the manufacturing steps and lowering the producing efficiency; the trimmer is expensive, and the cost is high. In high-accuracy grinding, a machine tool needs to be further equipped with an in-process trimming device, which also increases the design difficulty and manufacturing cost of the machine tool. In the prior art, improvement on the self-sharpness of the diamond grinding wheel is merely limited to improvement on trimming gap, while the problems of long time and high cost of trimming the grinding wheel still cannot be solved. The grinding wheel with the composite binding agent uses a composite binding agent made from ceramic powder and bronze powder, but the ceramic powder, having a relatively high level of fire resistance, needs to be smelted at 1700° C., which is higher than the sintering temperature of the grinding wheel, and the ceramic powder is not easy to disperse uniformly during the sintering process, having limited function in improving the grinding efficiency and the service life of the grinding wheel.